Process for manufacturing expanded and corrugated heat exchanger cores from metal strip material

ABSTRACT

A process for producing a corrugated heat exchanger dissipator for a tube and dissipator core, comprises forming in an elongate metal sheet material a plurality of longitudinally spaced sets of longitudinally extending slots with the slots of successive sets longitudinally aligned to form a plurality of parallel straps with the straps of successive sets in alignment, bending the straps of each set and the corresponding straps of successive sets alternately in opposite directions relative to the plane of the sheet, and bending the solid areas between the sets transversely in alternate opposite directions to corrugate the sheet and interfit the straps of adjacent sets.

United States Patent [1 1 Chartet Dec. 4, 1973 [54] PROCESS FORMANUFACTURING 1,899,080 2/1933 Dalgliesh 165/153 EXPANDED AND CQRRUGATEDHEAT 3,162,942 12/1964 Christman 29/455 LM EXCHANGER CORES FROM METALSTRIP a??? 2132 29/455 MATERIAL 2,537,026 1/1951 Brugger 72/186 x [75Inventor; Andre Chart, Meudon, prance 3,433,044 3/ 1969 Rhodes et a1.72/186 [73] Asslgneez zz z i t z g z s Primary ExaminerCharles W. Lanhamn e e rance Assistant Examiner-D. C. Reiley, Ill [22] Filed: Jan. 11,1972 Attorney-linirie and Smiley Appl. No.: 217,045

Related US. Application Data Division of Ser. No. 94,238, Dec. 1, 1970,Pat. No.

US. Cl

Int. Cl

Field ofSearch 72/324, 29/6.1, 29/455 LM, 72/379,113/116 A, 113/118 RB21k 27/06,B2ld 31/04 ..113/116 Y, 116 A,

113/118 R, 118 D; 29/455 LM, 157.3 R, 6.1; 165/152, 153, 181, 182,183;72/185, 186,

References Cited UNITED STATES PATENTS Zeider 113/118 R [57] ABSTRACT Aprocess for producing a corrugated heat exchanger dissipator for a tubeand dissipator core, comprises forming in an elongate metal sheetmaterial a plurality of longitudinally spaced sets of longitudinallyextending slots with the slots of successive sets longitudinally alignedto form a plurality of parallel straps with the straps of successivesets in alignment, bending the straps of each set and the correspondingstraps of successive sets alternately in opposite: directions relativeto the plane of the sheet, and bending the solid areas between the setstransversely in alternate opposite directions to corrugate the sheet andinterfit the straps of adjacent sets.

8 Claims, 9 Drawing Figures PAIENIEE 4 BIS sum 3 or 3 set of straps tobecome imbricated between each other.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a radiatorof which the core This is a division of application Ser. No. 94,238,filed is provided with dissipators of the present invention.

Dec. 1, 1970.

BACKGROUND OF THE INVENTION This invention relates to radiators forcooling fluids, and radiators provided particularly for vehicles with acore of tubes between which are placed dissipators constituted ofcorrugated intercalaries.

It is known that the main quantity of the heat which is dissipated by aradiator of that type is dissipated through dissipators. In the radiatormanufacturing technics, which have already reached a high degree of lperfection, an attempt is made to form, in the sections of thedissipators which are located, between the consecutive tubes wall or rowof a core, disturbers with punctures, whereby the air passing throughthe core has to follow complex passages which improve the heatdissipation.

The invention has came from the surprising facts which have been foundthat the heat dissipation of a corrugated intercalary is at a maximum atthe level of the leading edge of siad dissipators and then decreasesrapidly. Besides, it has become apparent that it would be possible tosubstantially reduce the dissipator thickness if it was possible tomultiply the leading edges but without restricting the contact surfacebetween the dis sipator and the tube wall. It has also become apparentthat the disturbers formed up to now into the dissipators, excessivelyincreased the loss of the air load passing through the core, whereby theair volume, that is the air mass, passing through the core is thusreduced of course to the prejudice of the quantity of the dissi patedheat.

SUMMARY OF THE INVENTION This invention embodies a new disturber intaking the above conditions into consideration and allowing toappreciably increase, the heat dissipation for a radiator having aspecified weight of metal constituting the dissipators, or toappreciably reduce the weight of metal constituting said dissipators fora same heat dissipation capacity of the radiator.

According to the invention, the dissipator has continuous supportingareas on the tube wall between which it is placed, said continuous areasbeing connected to each other by folded straps, alternately bent in oneway and in the other way, the straps of same bend of each foldstretching in parallel to each others whereby the straps coming next arerespectively imbricated by each other.

The invention also relates to a process for manufacturing the abovementioned dissipator. According to this second arrangement, parallel andlengthwise set of slots are made, said slots being separated by acontinu ous section, in the lengthwise way of a thin strip to delimitparallel straps, the delimited straps are performed by a same lot ofslots to fold them alternately one way and to the other, the straps, inline, made from two successive sets of slots having their curveopposite, the strip is corrugated at the level of each continuoussection separating each set of straps and the so-corrugated stripadvances while being retained in the undulated section thereof, whichcauses the straps of successive FIG. 7 is a slightly enlarged sectionalview and shown I along line VIIVII of FIG. 5.

FIG. 8 is a diagrammatic view illustrating a development of theinvention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a radiator in which 1and 2 designate two water boxes provided with connection tubes 3 and afilling flange 4. The water boxes overlap collectors 5 and 6 in whichrun the ends of the core tubes 7. Dissipators 8 are placed between eachtube or row of tubes '7 to form exchange secondary-surfaces between thefluid circulating into tubes 7 and the fluid passing through the core.

To form the dissipators 8, a very thin metallic strip 9 is utilized, asthin as some hundredths of millimeters, for instance made of copper,brass or aluminum, and sets of slots 10, 10a, etc. of a similar lengthare made in the lengthwise way on said strip. Each set of slots isseparated by a solid portion 11 designed to form the supporting surfacefor the dissipator on the wall of tubes 7 of the core, this supportingsurface being continuous from one to the other lateral edges of strip 9,as shown in FIG. 2. t

The slots 10, 10a, etc. are for instance made with roller 12 FIG. 3 butsaid slots could also be made by a press or by any other means.

Upon completion of slots, the strip 9 is preformed for example with asecond set of rollers 13 (FIG. 3) working successively on twopre-slotted sections of strip, that is, with reference to FIG. 2 on thetwo pre-slotted sections 10 and 10 This preforming causes the lengthwisepre-corrugations of successive straps delimited by slots 10, 10a. Thus,two successive straps, such as 14 and 14a are respectively preformed toturn their concavity up and down, and the two next straps such as 15 and15a are formed in the opposite direction, while the space 11,,separating the two slots 10,, 10,, is not preformed. Thus, aredelimited, with the successive straps, approximately alternate sinusoidsall along the strip 9. The bend of straps can be not continuous, saidstraps being then folded at a median section and thus delimiting twosections obviously linear on each side of the folding line.

Further to forming these pre-corrugations', it has been foundadvantageous to curve each strap in the cross-section way, for exampleby forming a median fold 16a which can be easily obtained by the samerol lers as those performing the above described preforming or beforethis operation, with the rollers making the slots 10, 10a. Thetransversal curve given to each strap is also alternated. As an example,with reference to FIG. 7, we see that the strap 14 is curved in a wayopposite to the one of the adjacent strap 15. The result of said curveis first to slightly operate the adjacent lateral edges of twosuccessive straps as shown for edges a and b of straps l4 and 15. Saidcurve also makes possible a folding of the straps more important thanthe one shown on FIG. 2 but only in one way. The curve also makes thestraps more rigid and finally is designed to create a turbulence in thefluid flow running through the core in the direction of the arrow f ofFIG. 7 and consequently to increase the quantity of the dissipated heatfor a same surface of metal.

An additional operation consists of corrugating the pre-formed strip,exactly as it is made upon the manufacturing of corrugated dissipators,which is most of the time performed with a set of rollers, such asrollers 16. Said corrugation has the effect to alternately bend inopposite directions the solid portions 11 separating each set ofpre-corrugated straps.

When the corrugated strip is discharged from rollers 16 and because thepreforming of straps l4 and 15 between portions 11, each section hasbowed portions 17 defined said straps. The so-corrugated strap passes ona guide 18 and is directed under a block 19 which reduces the advancethereof in the way indicated by the arrow f said advance being causedthereto by the rollers. The height of block 19 is adjusted in such a waythat the successive folds formed by the strip be partly crushed as theadvance of the strip is reduced. Thus the pre-corrugation of the strapsis increased, said straps being folded in the way they arepre-corrugated or prefolded and the straps of a fold being irnbricatedby those of next fold. For example, the strap 15 of FIG. 2 is thusbrought between the straps 14a and 14b as well shown in drawing of FIGS.4 and 5. On FIG. 4 it is shown that straps 14 and 14a which wereoppositely folded are set in parallel to each other, it is the same forstraps 15, 15a which are folded in the other way. It is also noticedthat two continuous sections are respectively set on one and the otherof the two sides of the formed dissipator, which is especially noticedfor sections 11 and 11 of FIG. 2 which respectively appear at upper andlower sections of two successive folds of the dissipator shown on FIG.4.

FIG. a shows a case where the straps, instead of presenting a continuousbend are pre-folded substantially at their median section, to formangles 20, thus each of them defining appreciably linear segments 21,

The way the straps overlap each other depends on the height of the freepassage between guide 18 and block 19 of FIG. 3. By sufficientlyreducing this passage, it becomes possible that each strap correspondsto more than two successive folds of the constituted corrugateddissipator. When the friction made by the block is substantially thesame as the one made by the guide 18, it can then be obtained that thesection 11 be shifted by half-a-pitch in comparison with section 11,,that is be placed just at the median section of the space separating thetwo sections 11 and 11 of FIG. 5.

On the contrary, if the friction made by block 19 is different of theone made by the guide 18, it is then obtained, as shown in FIG. 8, anadditional deformation which can be set as desired and which can allowif desired that the section 11 be strictly in line with the section 11,,whereby said solid surfaces of the dissipators can rest on sections, inline, of two consecutive tubes or rows of tubes 7.

The invention is not restricted to the embodiment shown and described indetail for various modifications thereof can moreover be applied to itwithout departing the scope of the invention. More particularly thelength of the straps can be different according to needs, for example itcan progressively change in the direction of the air circulation,whereby the convection coefficient is modified depending on the airheating.

I claim:

1. Method for manufacturing an elongated member of heat conductingmaterial having a generally zigzag configuration, comprising the stepsof:

slitting successive portions of a metal strip with spaced groups ofparallel longitudinal slots defining spaced groups of parallellongitudinal straps; bending the straps of each group alternately inopposite directions from said strip with aligned straps of successivegroups bent in opposite directions; bending said strip transverselythereof in opposite directions alternately between successive groups ofstraps in zig-zag configuration, and

interfitting the bent straps of successive groups.

2. Method according to. claim 1 comprising compressing the adjacentzig-zag portions of said strip to increase the interfitting of saidstraps.

3. Method according to claim 1 wherein said straps are arcuately bentlongitudinally.

4. Method according to claim 1 wherein said straps are angularly bentlongitudinallyv 5. Method according to claim 1 comprising the step ofuniformly spacing the solid areas between said strap groups on twoopposite sides of the member so that each area on one side isintermediately spaced between two adjacent areas on the other side.

6. Method according to claim 1 comprising the step of uniformly spacingthe solid areas so that corresponding areas on the opposite sides arealigned transversely of the member.

slots so that the straps have different widths.

1. Method for manufacturing an elongated member of heat conductingmaterial having a generally zigzag configuration, comprising the stepsof: slitting successive portions of a metal strip with spaced groups ofparallel longitudinal slots defining spaced groups of parallellongitudinal straps; bending the straps of each group alternately inopposite directions from said strip with aligned straps of successivegroups bent in opposite directions; bending said strip transverselythereof in opposite directions alternately between successive groups ofstraps in zig-zag configuration, and interfitting the bent straps ofsuccessive groups.
 2. Method according to claim 1 comprising compressingthe adjacent zig-zag portions of said strip to increase the interfittingof said straps.
 3. Method according to claim 1 wherein said straps arearcuately bent longitudinally.
 4. Method according to claim 1 whereinsaid straps are angularly bent longitudinally.
 5. Method according toclaim 1 comprising the step of uniformly spacing the solid areas betweensaid strap groups on two opposite sides of the member so that each areaon one side is intermediately spaced between two adjacent areas on theother side.
 6. Method according to claim 1 comprising the step ofuniformly spacing the solid areas so that corresponding areas on theopposite sides are aligned transversely of the member.
 7. Methodaccording to claim 1 wherein the slitting step produces equally spacedlongitudinal slots so that the straps are equal in width.
 8. Methodaccording to claim 1 wherein the slitting step produces variably spacedparallel longitudinal slots so that the straps have different widths.